I just started playing with this new Live Corners feature that is being talked about in Illustrator CC. In my opinion, it is very badly designed & implemented. Reasons for saying so:
1) It is okay only for objects that have nothing else in the background. If I want to apply Live Corners to specific portions (corners) of object(s) which has some other objects lying beneath, I have to carefully and patiently select those specific corners with the DS tool (click, shift-click, shift-click, etc.). I cannot marquee-drag & select just those specific corners since if I do that, the object will move. Or else I have to lock the objects in the background or isolate the object to which I want to apply corners.
The official video showing the Live Corners feature cleverly demonstrates this only on a unfilled object having nothing else in the background (there is just the artboard beneath the object).
2) Why do I need to select an object or specific corners of an object to apply Live Corners to them? Why can't it work on a non-selected object? Also since the application of Live Corners is tied to the DS tool and since this tool selects the object if I click on it, I'm always having to deselect those corners or objects to which I don't want to apply Corners. Many times I am applying corners to objects to which I don't intend to apply corners. Lots of wasteful repetitive clicks.
3) Selecting a perfect circle with the Direct Selection tool shows just 2 Live Corner widgets. Why only 2? Why not 4 (the circle contains 4 segments, right)? And even on dragging those 2 widgets, nothing seems to happen. What nonsense? Does no one test out these things?
4) I cannot create a perfectly rounded rectangle (for buttons, etc.) with Live Corners, starting with a normal rectangle (to which no corners are applied). There is always a small segment left where the two corners are supposed to meet. A perfect round rectangle should just contain 6 anchor points, no more. Try to create the same with Live Corners and you will see what I mean - you'll be disappointed with how it works.
5) There is no quick and easy way to 'convert' all the Round Corners Dynamic Effect applied to objects into Live Corners.
6) Once I have applied a specific Live Corner radius value to a single corner, there is no way to quickly apply the same value to another corner of the same object or a different object. Not giving this option is just so lame, imo.
7) While interactively dragging to apply Live Corners, say to a rectangle, there could be minor variation in the corner value applied to one corner and the other corner (if I had selected them individually). If I want to select all such corner radiuses which lie within a tolerance range and quickly change either their radius value or the corner type, I cannot do it (there is no such setting available) C'mon Adobe, you could do better than this!
8) I cannot set a radius value first, interactively see how it will look when applied but without applying it (by just hovering over a corner) directly and then apply it if I like the appearance by simpl clicking. Rather I have to work backwards - I have to first select a corner of an object and then apply a radius value to it.
9) If I have applied Live Corners to an object and then do some destructive edit to just one corner, the other corners also go bust. Why? Why can't the other corners actively adjust themselves to the edit made to one corner?
10) I do not get the feedback about the radius value that is applied on a corner by hovering over it.
11) Sometimes you need to apply another Corner to an existing corner. Here:
Image may be NSFW.
Clik here to view.
As shown, I want to first apply an inverted round corner to one side of a corner and then apply normal round corners twice (shown with red arrows) to the same corner. This is not possible to do directly with Live Corners feature since there is no concept of removing the "liveness" of a corner so that another type of corner could be applied, if desired.
12) Selecting a corner or corners to which Live Corners is applied is again not elegant. I cannot marquee drag the corner, especially if it is internal to a bigger object without running the risk of moving or changing something else in the artwork.
13) Relative Rounding method does not seem to work with Chamfered Corner. Is it not supposed to work? Then why is it available/enabled?
Overall my experience using this new Live Corners feature has not been exciting enough to make me embrace it - in fact many ills plague it, as with many other new features from Adobe.
To get my work done, I have been using a plug-in called Dynamic Corners (from Astute Graphics) that works superbly well & overcomes the silly & lame implementation of Adobe's Live Corners. Adobe can learn tremendously from these plug-in makers & design their tools to meet & delight the users' needs instead of pushing these short-sighted features down our throats.
Anyone who values his/her creativity and time, I'd highly recommend seeing this short Youtube video (Dynamic Corners in Adobe Illustrator : http://www.youtube.com/watch?v=MLn2ZjgSQp8) which beautifully explains how beautifully Dynamic Corners works.